The present disclosure relates to a method of manufacturing a solid-state imaging element in which photoelectric conversion units are arranged on a curved surface curved three-dimensionally, a solid-state imaging element obtained by such a method of manufacturing, and electronic apparatus provided with such a solid-state imaging element.
Further, the present technique relates to a solid-state imaging apparatus and an electronic apparatus such as a camera provided with the solid-state imaging apparatus.
In imaging devices such as cameras in which a solid-state imaging element and an imaging lens are combined, the imaging lens is configured so as to be arranged on the light-receiving surface side of the solid-state imaging element. In such an imaging device, when a subject is imaged by the imaging lens, focus position deviation is generated in the center and peripheral parts of the imaging surface due to lens aberration called field curvature. Thus, a configuration has been proposed in which, depending on the field curvature of the imaging lens, a curved surface curved three-dimensionally is formed and photoelectric conversion units are arranged with this curved surface as the imaging surface (light-receiving surface) of the solid-state imaging element. In this manner, the importance of the correction of the field curvature (lens aberration) is eliminated by the combination of a plurality of lenses. As a method of manufacturing a solid-state imaging element in which photoelectric conversion units are arranged on a curved surface in such a manner, the following two methods have been disclosed, for example.
The first method has a curved surface in an element distribution region and uses a package main body in which suction holes are formed at a bottom portion. In such a case, solid-state imaging elements are arranged to face each other on a curved surface coated with a fixing agent, attached to the curved surface by reducing the pressure of the interval portion between the solid-state imaging elements and the curved surface through the suction holes, and fixed with the fixing agent (for further details, refer to Japanese Unexamined Patent Application Publication No. 2003-243635 (in particular, paragraphs 0013 to 0014 and FIG. 2) described below).
The second method has an opening portion and uses a wiring substrate formed using a material having a thermal expansion coefficient greater than the solid-state imaging elements. In this case, first, the wiring substrate and the solid-state imaging elements are bonded through protrusion electrodes. Then, the contraction coefficient of the wiring substrate becomes greater than the contraction coefficient of the solid-state imaging elements due to the cooling action after heating and cooling, whereby compressive force is applied to the solid-state imaging elements due to the difference in the contraction coefficient and the solid-state imaging elements are caused to curve (for further details, refer to Japanese Unexamined Patent Application Publication No. 2004-146633 (in particular, paragraphs 0017 to 0020 and FIG. 1) described below).
The electronic apparatus having an imaging function such as a camera combining a solid-state imaging apparatus (image sensor) and an imaging lens is configured with the imaging lens arranged on the light receiving surface of the solid-state imaging apparatus. In this kind of imaging apparatus, when a subject is imaged by the imaging lens, deviation of the focus position is generated at the center portion and peripheral portion of the imaging surface due to imaging surface curvature called lens aberration. Here, configurations in which a curved surface curved three-dimensionally according to the imaging surface curvature of the imaging lens is formed, and this curved surface is set as an imaging surface (light receiving surface) of the solid-state imaging apparatus, and a photoelectric conversion unit is arranged have been proposed (for example, refer to Japanese Unexamined Patent Application Publication No. 2003-188366, Japanese Unexamined Patent Application Publication No. 2003-243635, and Japanese Unexamined Patent Application Publication No. 2004-146633). In this manner, correction of the imaging surface curvature using a combination of several lenses may be avoided.
On the other hand, there are imaging apparatuses provided with a zoom lens and capable of zoom imaging. Hitherto, imaging apparatuses capable of zoom imaging have been configured provided with a solid-state imaging apparatus having a flat imaging surface and a zoom lens formed of a plurality of lens groups.